SFRP2 and systemic sclerosis: Cluster 8 (SFRP4/PRSS23) was identified as a myofibroblast-like cluster in our LS dataset based on our Scleroderma Center’s prior findings in SSc skin [9], with this population expressing shared upregulated genes SFRP2, PRSS23, SFRP4, ADAM12, and ACTA2 (Table S3).